Hermetically sealed crystal assembly



Jan. 6, 1948n Y H. xEnsfY-mw 2,434,043

noma suman caws-fm. ssamm Filed Deo. 8, 1944 2 Sheets-sheet 1 ffenrylemkaz'u.-

' Jan. 6, 1948. H, KERsHAw HERNBTICALLY SEALED CRYSTAL ASSEMBLY Filed Dec. 8, 1944 2 Sheets-Sheet 2 302.9 l l l l////]///I/// Patented Jan. 6, 1948 HERMETICALLY SEALED CRYSTAL ASSEMBLY l Henry Kershaw, Belleville, N. J. Application December 8, 1944, Serial No. 567,259

s claims. (c1. 1v1-327) My invention relates to a, hermetlcally sealed crystal assembly for use in connection with circuits of radio transmitting or receiving sets or the like.

An important object of the invention is to provide a device of the above mentioned character which will withstand the jars or hard usage encountered when installed upon a radio set carried by an airplane or the like.

A further object of the invention is to provide a device of the above mentioned character which Will retain the crystal and associated elements free from contact with the atmosphere or under vacuum.

A further object of the invention is to provide a device of the above mentioned character, so constructed that the casing may be readily evacuated after the elements are assembled therein, and the tipped vacuum tube will be covered.

A further object of the invention is to provide a vacuum tight casing having welded telescoping parte. effecting a vacuum tight joint.

A further object of the invention is to plate the casing after welding, thus reducing the porosity of the minimum.

Other objects and advantages of the invention will be apparent during` the course of the following description.

In the accompanying drawings, forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

Figure 1 is an exploded perspective view of a piezo crystal holder embodying my invention,

Figure 2 is a central longitudinal section through the assembly,

Figure 3 is a longitudinalsection 3--3 of Figure 2,

Figure 4 is a side elevation, parts broken away, and parts in section, showing the manner of welding the telescoping parts of the casing,

Figure 5 is an enlarged fragmentary section through the casing, after welding, showing the outer surface plated,

Figure 6 is a side elevation of the completed assembly.

casing and the welded joint to the #n on line Figure 7 is a central longitudinal sectionv through a modified form of assembly Figure 8 is a horizontal section taken on line 8-8 of Figure '7, and

Figure 9 is a similar view taken on line 9-9 of Figure 7.

In the drawings, wherein for the purpose of illustration is Ashown a preferred embodiment of my invention, the numeral I0 designates a metal casing, which is preferably cylindrical. One end of this casing is closed by a head II while the opposite end of the casing is open and is provided with an annular flange or skirt I 2, of larger diameter than the casing IU, affording a shoulder I3. The open end of the casing IIl is covered by a metal head I4 having an annular flange or skirt I5, to fit snugly within the annular flange or skirt I2. The head I4 is formed to provide a holn low rib I 8, affording a passage I1. This rib ex tends axially outwardly of the flange or skirt I5 and extends diametrically of the head I4. The inner side and ends of the passage I1 are open and in communication with the interior of the easing I0, as shown. The hollow rib I 6 is provided with outwardly punched apertured portions I8 and I9, as shown.

Arranged within the cylindrical casing IU is a cylindrical insulating housing 28 having a chamber or recess 2I, which is preferably square iny horizontal cross section. At its top, the housing 20 has a cylindrical recess 22 for receiving the reduced extension 23 of an insulating cap or end 24. The opposite end of the insulating housing 20 rests upon the face of the head I4.

Arranged within the square chamber or recess 2| are metal electrodes 25 and 26, and arranged between these electrodes is a fiat crystal 2l, which may be formed of quartz and ground to a selected thinness, depending upon the frequency to be maintained in the radio set or circuit in connection with which the device is used. These elements 25, 26 and 21 are loosely mounted within the chamber 2I and may be moved axially therein within limits and there is a. slight space or clearance between the edges of these elements and the walls of the chamber 2|. The electrode 26 electrically contacts with the head I4 while the electrode 25 electrically contacts with the square body portion 28 of a metal leaf spring 29 having a spring arm 30, extending over the same in spaced' relation. This spring arm is preferably tapered and is provided at its reduced free end with the knob 3I.to enter a recess 32. The body portion 28 is loosely mounted within the chamber or recess 2I and forces the metallic electrodes 25 and 26 into engagement with the quartz crystal 2l.

A lead wire 33 is welded to the body portion 28 at 34, and this lead wire extends through a recess 35 and an opening 36 formed in the insulating body portion 20. A lead wire 31 is welded to the rib I6 as shown at 38. The lead wire 33 extends through the outwardly punched apertured portion uI 8 and has a gas or vacuum tight joint therewith,

3 which is effected by means of a glass bead 33' fused thereon. A glass tube 39 is fused to the outwardly punched apertured portion I9.

The numeral 4|) designates an insulating base, carrying tubular metallic terminals or plugs 4I and 42. This base 4I) has a reduced extension 33', having a pressed nt in the skirt I5. I'he tubular terminal 4| receives the wire 33, while the tubular terminal 42 receives the wire 31. The ends of these wires extend outwardly beyond the tubular terminals and these wires are electrically connected with the tubular terminals by solder 43, the wires being subsequently severed flush with the solder. The insulating base 43 has a groove 43' and a central recess 4I', leading into this groove.

In assembling the various parts of the device, the quartz crystal 21 is arranged between the electrodes 25 and 26 and these elements are introduced into the chamber 2| and the leaf spring 29 is arranged within this chamber outwardly of the electrode 25. The wire 33 which is previously welded to the leaf spring is passed through the opening 3B. The insulating cap 24 may now be applied to the end of the housing 20 and the knob 3| will enter the recess 32. This knob now serves to center the leaf spring within the chamber 2|, preventing any tendency for the leaf spring to bind in the chamber 2 I. The parts thus assembled may now be introduced into the metal casing III and the wire 33 will project through and beyond the iiange or skirt I2. The wire 33 is now passed through the outwardly punched apertured portion I8 of the metal head I4 and this metal head and its skirt I are now inserted into the skirt I2, the skirts telescoping and having a. snug fit. The inward movement of the head I4 is limited by its engagement with the shoulder I3. A vacuum or gas tight joint is now effected between the portion I3 and wire I3 by fusing the glass bead 38 to these parts.

With the parts thus assembled, the telescoping tubular skirts I2 and I5 are welded together for effecting a gas or vacuum tight joint. This is accomplished by bringing the telescoping skirts I2 and I5 into engagement with inclined faces 44 of tubular electrodes 45, insulated at 45. The telescoping skirts I2 and I5 are now moved axially toward the tubular electrodes 45 whereby these electrodes engage the free corners 41 of the skirts, moving the skirt I5 radially outwardly and the skirt I2 radially inwardly. The welding circuit is closed during this action and an annular weld 43 is effected between the skirts I2 and I5 and the weld is gas or vacuum tight. The meth- 0d of welding the skirts I2 and I5 is fully disclosed the casing in any desired amount, prior to tipin my copending application for Method of and apparatus for welding, filed May 2, 1944, Serial No. 533,719, which has matured into Patent 2,385,710, issued September 25, 1945.

The next step is to evacuate the casing I3, which is effected by connecting the tube 33 with a source of vacuum. After the desired degree ofl vacuum is obtained, a small amount of an inert gas, such as argon, is introduced into the casing through the tube 39. This introduced argon does not ordinarily materially reduce the degree of vacuum within the casing III. Attention is called to the fact that since the glass tube 33 communicates with the passage I1, the tube 33 will have communication with the interior of the casing I3 due to the clearance between the edges of elements 25, 25, V21 and 23 and the walls of the chamber 2i. After the introduction of the inert ping of the vacuum tube.

All metal is porous to some extent and to reducethe porosity of the casing I3, head I4 and the welded joint 48 to the minimum porosity, after the welding is eifected, I plate the outer surface of the casing I0, head I4 and annular weld 43 with a metal plating 50, Figure 5.

The Vcasing I0 and head I4 maybe formed o! any suitable metal and the head I4 or parts thereof to which the glass is to be fused should be formed of a metal having the same coeiilcient of expansion as glass.

After the welding and plating, the insulating base 48 is applied to the skirts I2 and I5 and the Wires 33 and 31 pass through the tubular terminals 4I and 42 and attached thereto by the solder 43. The tip 49 may now project into the recess 4I.

The terminals 4I and 42 are usually plugged into the radio circuit so that the quartz crystal 21 is connected across the illament and grid of the vacuum tube. The use of these devices is well known as indicated by Patents 2,289,950; 2,295,- 990; and 2,339,198.

In Figures 'l to 9 inclusive I have shown a modiiication of the invention. In these gures, 25* and 23'L designate the electrodes and 21n is the quartz crystal arranged between the electrodes. The electrode 25* contacts with the body portion 23 of the spring 23, while the electrode 25l engages a metallic contact 23b arranged beneath it and being of the same shape and size. The metallic contact 23-1 rests upon an insulating strip 23, which is also square. This insulating strip is supported upon the upper end of the head I4. The insulating strip 23= has an opening 2licl cut therein, for the passage of the wire 31. This wire is soldered or welded to the contact 23b as shown at 31. The wire 31 is not electrically connected with the head I4 but passes thru an outwardly punched apertured portion I3' and is soldered or welded to the contact 23h, as stated, and is insulated from the head I4 by a glass bead 31' fused or welded to these parts, to form a vacuum tight joint.

All other parts of the device remain identical with those shown and described in connection with the first form of the invention.

It is to be understood that the forms of my invention herewith shown and described are to be taken as preferred examples of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is;

1. A hermetically sealed crystal assembly comprising a metallic casing having one end closed and the other end open, an insulating housing mounted within the casing, electrodes mounted within the housing to receive a crystal between them, means to move the electrodes together, a metallic head arranged Within the open end of the casing and having a gas tight joint therewith, the head having apertures, means to evacuate the metallic casing through one aperture of the head, a wire electrically connected with one electrode and extending thru the other aperture, an insulating bead to seal the wire within its aperture, a second wire electrically connected prising a metallic casing having one end closed s and its opposite end open, an 'insulating housing within the casing, electrodes within the housing to receive a crystal between them, means to move the electrodes together, a metallic head for inf sertion within the open end of the casing, said metallic head having a hollow rib providing a passage upon' its inner side, said head having an evacuating aperture leading into the passage `and having asecond aperture, the head having a gas tight joint with the casing, means to move the electrodes together, means to close the evacuating aperture, a wire electrically connected with one electrode and passing through the second aperture and having a sealed joint therein, a second Wire connected with the head, the head being electrically connected with the other electrode, an insulating base mounted upon the open end of the casing and covering the metallic head, and terminals carried by the base and having electrical connection with the wires.

3. A hermetically sealed crystal assembly com t nected with the contact and extending thru one i aperture, a glass bead to seal the wire within the aperture, a second contact engaging the other electrode, an insulating strip arranged between the second contact and metallic head, a second wire passing thru the other aperture and attached to the secondcontact, a glass bead sealing the second wire within the last named aperture, an insulating base mounted upon the open end of the casing, and terminals carried by the base and electrically connected with the wires.

, 4. A hermetically sealed lrystal assembly comprising a metallic casing having one end closed and its opposite end open, an insulating housing within the casing and having one end closed and its opposite encl open, the closed end of the housing being arranged next to the closed end of the casing, overlapping electrodes arranged within the housing and arranged generally parallel with the closed end of the housing, a crystal disposed between the electrodes, a metallic head inserted within the open end of the casing and having a hollow rib providing a passage which is open upon its inner side, the head having a gas tight joint with the casing, means tending to move the electrodes together, the head having means whereby the casing may be evacu- 'ated through the passage, a wire electrically connected with one electrode, a second wire having electrical connection with the other electrode, an insulating base mounted upon the open end of the casing and covering the head, and terminals carried by the base` and having electrical connection with the wires.

5. A hermetically sealed crystal assembly, cmprising a metallic casing having .one end closed and its opposite end open, an insulating housing within the casing and having one end closed of the casing, a metallic head inserted within the open end of the casing and having an interior passage and also having means whereby the casing may be evacuated through the passage, the head having a gas tight joint with the casing, overlapping electrodes arranged within the housing and arranged generally parallel with the closed end of the housing, a crystal disposed between the electrodes, a metallic element contacting with one electrode and having a resilient part acting against the closed end of the housing, a wire electrically connected with the metallic element, a second wire having electrical connection with the other electrode, an insulating base mounted upon the open end of the casing and covering the head, and terminals carried by the base and having electrical connection with the wires.

' 6. A hermetically sealed crystal assembly, comprising a metallic casing having one end closed and its opposite end open, an insulating housing within the casing and having one end closed and its opposite end open, the closed end of the housing being arranged next to the closed end ofthe casing, a metallic hea'd covering the open end of the casing and having a gas tight joint with the casing, overlapping electrodes arranged within the housing and arranged generally parallel with the closed end of the housing, a crystal disposed between the electrodes, a spring acting upon one electrode and acting against the closed end of the housing, a wire electrically connected with one electrode, a second Wire having electrical connection with the other electrode, an insulating base mounted upon the open end of the casing, and terminals carried by the base and having electrical connection with the wires.

7. A hermetically sealed crystal assembly, comof the casing, a metallic head covering the open end of the casing and having a gas tight joint with the casing, overlapping electrodes arranged within the housing and disposed generally pari allel with the closed end of the housing, a crystal disposed between the electrodes, means to move the electrodes together, a wire electrically connected with one electrode, a second wire having electrical connection with the outer electrode, an insulating base mounted upon the open end of the casing, and terminals carried by the base and having electrical connection with the wires.

8. A hermetically sealed crystal assembly, comprising a metallic casing having one end closed and -its opposite end open, an insulating housing within the casing and having one end closed and its opposite end open. the closed end of the housing being arranged adjacentto the closed end of the casing, overlapping electrodes arranged within the housing and arranged generally parallel with the closed end of the housing, a crystal disposed between the electrodes, means to move the electrodes together, a metal head inserted within the open end of the metal casing and having a marginal skirt extending axially of the casingthe skirt and casing being welded together adjacent to the outer end of the skirt, a metallic plating applied to the outer face of the casing and head and covering the welded joint, an insulating base arranged near the open 7 end of the casing, terminals carried by the base. mm means electrically connecting one terminal with STATES PATENTS one electrode, and means electrically connecting Number Name Date the other terminan with the other electrode. 861,242 Edison July 2s, 190': HENRY KERSHAW. 5 2,228,087 Rose Jan. '7, v1941 2,203,486 Bone June 4, 1940 REFERENCES CITED 03f545 Peterson P June 4, 1940 6 ,707 Fair Oct. 28, `1941 The fnllowing references are of record in the 2,277,871 Mitchell et al Mar. 31. 1m

me of this patent: 

